Auth0 React Integration

Add authentication to React single-page applications using @auth0/auth0-react.

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Prerequisites

• React 16.11+ application (Vite or Create React App) - supports React 16, 17, 18, and 19
• Auth0 account and application configured
• If you don't have Auth0 set up yet, use the auth0-quickstart skill first

When NOT to Use

• Next.js applications - Use auth0-nextjs skill for both App Router and Pages Router
• React Native mobile apps - Use auth0-react-native skill for iOS/Android
• Server-side rendered React - Use framework-specific SDK (Next.js, Remix, etc.)
• Embedded login - This SDK uses Auth0 Universal Login (redirect-based)
• Backend API authentication - Use express-openid-connect or JWT validation instead

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Quick Start Workflow

1. Install SDK

npm install @auth0/auth0-react

2. Configure Environment

For automated setup with Auth0 CLI, see Setup Guide for complete scripts.

For manual setup:

Create .env file:

Vite:

VITE_AUTH0_DOMAIN=your-tenant.auth0.com
VITE_AUTH0_CLIENT_ID=your-client-id

Create React App:

REACT_APP_AUTH0_DOMAIN=your-tenant.auth0.com
REACT_APP_AUTH0_CLIENT_ID=your-client-id

3. Wrap App with Auth0Provider

Update src/main.tsx (Vite) or src/index.tsx (CRA):

import React from 'react';
import ReactDOM from 'react-dom/client';
import { Auth0Provider } from '@auth0/auth0-react';
import App from './App';

ReactDOM.createRoot(document.getElementById('root')!).render(
  <React.StrictMode>
    <Auth0Provider
      domain={import.meta.env.VITE_AUTH0_DOMAIN} // or process.env.REACT_APP_AUTH0_DOMAIN
      clientId={import.meta.env.VITE_AUTH0_CLIENT_ID}
      authorizationParams={{
        redirect_uri: window.location.origin
      }}
    >
      <App />
    </Auth0Provider>
  </React.StrictMode>
);

4. Add Authentication UI

import { useAuth0 } from '@auth0/auth0-react';

export function LoginButton() {
  const { loginWithRedirect, logout, isAuthenticated, user, isLoading } = useAuth0();

  if (isLoading) return <div>Loading...</div>;

  if (isAuthenticated) {
    return (
      <div>
        <span>Welcome, {user?.name}</span>
        <button onClick={() => logout({ logoutParams: { returnTo: window.location.origin } })}>
          Logout
        </button>
      </div>
    );
  }

  return <button onClick={() => loginWithRedirect()}>Login</button>;
}

5. Test Authentication

Start your dev server and test the login flow:

npm run dev  # Vite
# or
npm start    # CRA

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Detailed Documentation

• Setup Guide - Automated setup scripts (Bash/PowerShell), CLI commands, manual configuration
• Integration Guide - Protected routes, API calls, error handling, advanced patterns
• API Reference - Complete SDK API, configuration options, hooks reference, testing strategies

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Common Mistakes

Mistake	Fix
Forgot to add redirect URI in Auth0 Dashboard	Add your application URL (e.g., http://localhost:3000, https://app.example.com) to Allowed Callback URLs in Auth0 Dashboard
Using wrong env var prefix	Vite uses VITE_ prefix, Create React App uses REACT_APP_
Not handling loading state	Always check isLoading before rendering auth-dependent UI
Storing tokens in localStorage	Never manually store tokens - SDK handles secure storage automatically
Missing Auth0Provider wrapper	Entire app must be wrapped in <Auth0Provider>
Provider not at root level	Auth0Provider must wrap all components that use auth hooks
Wrong import path for env vars	Vite uses import.meta.env.VITE_*, CRA uses process.env.REACT_APP_*
Using acr_values redirect for in-app MFA	Use useAuth0().mfa API for in-app enrollment/challenge/verify flows
Not catching MfaRequiredError	Wrap getAccessTokenSilently in try/catch and check instanceof MfaRequiredError
Making direct HTTP calls to MFA endpoints	Use the mfa property from useAuth0() — it handles token management automatically
Forgetting refresh tokens for step-up MFA	Set useRefreshTokens={true} on Auth0Provider when using interactiveErrorHandler="popup"

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Related Skills

• auth0-quickstart - Basic Auth0 setup
• auth0-migration - Migrate from another auth provider
• auth0-mfa - Add Multi-Factor Authentication
• auth0-cli - Manage Auth0 resources from the terminal

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Quick Reference

Core Hooks:

• useAuth0() - Main authentication hook
• isAuthenticated - Check if user is logged in
• user - User profile information
• loginWithRedirect() - Initiate login
• logout() - Log out user
• getAccessTokenSilently() - Get access token for API calls
• mfa - MFA API client for enrollment, challenge, and verification
  • mfa.getAuthenticators(mfaToken) - List enrolled authenticators
  • mfa.getEnrollmentFactors(mfaToken) - Get available enrollment factors
  • mfa.enroll(params) - Enroll new authenticator (OTP, SMS, Email, Voice, Push)
  • mfa.challenge(params) - Initiate MFA challenge
  • mfa.verify(params) - Verify MFA challenge and complete authentication

MFA Error Types (import from @auth0/auth0-react):

• MfaRequiredError - Thrown by getAccessTokenSilently when MFA is needed (has mfa_token and mfa_requirements)
• MfaEnrollmentError, MfaChallengeError, MfaVerifyError - Thrown by respective mfa.* methods

Common Use Cases:

• Login/Logout buttons → See Step 4 above
• Protected routes → Integration Guide
• API calls with tokens → Integration Guide
• Error handling → Integration Guide
• MFA handling → Integration Guide

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References

• Auth0 React SDK Documentation
• Auth0 React Quickstart
• SDK GitHub Repository